Fluid-actuated pressure equalizer for hydraulic brakes



Jan. 23, 1230 0. J. FROCK.

FLul D ACTUATED PRESSURE EQUAL ZER FOR HYDRAULIC BRAKES FILED FEB. 25,

INVENTOR 7. Face/r 5 2 v a \mlrlt I L A M All atente Jan. .11.?

OSCAR J. FROCK 01E WILMINGTON, DELAWE.

lEL'UIlD-ACTUATED PRESSURE EQUALIZER FOR HYDRAULIC BRAKES.

Applicationafiled February 25, 1922. Serial No. 539,179.

To all -w from it may concern:

Be it known that I. OSCAR J. FROCK, a citizen of the United States, residing at Wilmington, in the county of New Castle and 5 State of Delaware, have invented certain new and useful Improvements in Fluid- Actuated Pressure Equalizers for Hydraulic Brakes, of which the following is a specification. i

This invention relates to an improved pressure applying and equalizing device for use in a hydraulic brake structure of the type shown in my co-pendin application, filed January 27, 1922, Serial 0. 532,088.

One object of the invention is to provide an equalizer in which fluid may be placed under'pressure by pistons of separate cylinders and the pistons of the pressure cylinders moved in an operative direction by fluid forced into the presure cylinders above the pistons from a common actuating cylinder thus causing the pistons of the pressure cylinders to be operated under equal pressure. Another object of the invention is to so construct the pressure equalizer that the actuatin cylinder may be positioned between t e pressure cylinders and the cylinders cast in a single block if so desired.

Another object of the invention is to provide an improved construction of piston for the actuatingcylinder serving to raise fluid upwardly in the cylinder as the piston is forced downwardly thus permitting fluid in the actuating cylinder to be very effectively forced out of the actuating cylinder and into the pressure cylinders.

Another object of the invention is to pro vide the pressure cylinders with improved pistons which will be guided in their movement by stem extensions which extend 11pwardly into pockets formed upon the cylinder heads and to further so constructthese piston stems-that the formation of vacuums above the stems will be prevented.

Another object of the invention is to so construct this pressure equalizer device that the same principle may be used in pressure equalizers used for intake structures having the brakes arranged in pairs or in brake structures havin a separate pressure cylinder for each bra e.

Another object of the invention is to pro vide a pressure equalizer in which the va rious parts may be readily taken apart for cleanin and repairing when necessary.

This invention is illustrated in the accompanying drawings wherein:

" Figure 1 is a vertical sectional view through the pressure applying device.

Figure 2 is a View showing the device in modified form principally in vertical section and partially in elevation. Figures 4, 5 and 6 are semi-diagrammatlc viewsv in cross section showing various combinations of pressure and power cylinders.

This pressure equalizer is for use in connection with a brake structure such as shown in my co-pending application filed'January 27, 1922 and having Serial No. 532,088 and is provided with a powercylinder 1 and pressure cylinders 2. Each of the cylinders is 7 provided wth a side neck 3 having a passage 4 communicating with the interlor of the cylinder adjacent the lower end thereof so that fluid may pass into the cylinder and replenish fluid which may be lost during application of the brakes. An inwardly opening check valve 5 is provided for each neck so that the fluid may pass through the neck into the cylinder but will be prevented from passing out of the neck. If the fluid used is air, the valves 5 will extend directly to the atmosphere but if liquid is used pipes leading from a suitable reservoir will be suitably connected with the necks 3 about the valves.

The cylinders 2 maybe positioned upon opposite sides of the cylinder 1 as shown in Fig. 5 or the cylinder 1 may be positioned out of alinement with the cylinders 2 as shown in Fig. 4. If instead of providing two cylinders for the four brakes of the automobile, A5 it is desired to have a separate cylinder for each brake the cylinders 2 will be arranged about the cylinder 1 as shown in Fi 6. Tn

each form the cylinder 1 is provi ed with side ports 6 which communicate with the cyl- 1W inders 2 adjacent the upper ends thereof so that fluid may be forced from the cylinder 1 into the upper ends of the cylinders 2. If two cylinders 2 are used instead of a se arate cylinder for each brake, each cylin er lot will be connected with a pair of brakes and one may be connected with the front brakes and the other with the rear brakes or one may be connected with a front brake on one side of the autemebile and a rear brake lie upon the other side of the automobile and the other cylinder connected with the other two brakes. In the detailed views shown in Figs. 1, 2 and 3, the form shown in Fig. 4 has been specifically illustrated and reference will now be had to these figures.

Each of the cylinders 2 is provided with a thick base portion 7 having a passage 8 formed therein and provided with side passages 9. The passage 8 is closed at its lower end by a removable plug 10 and the side passages 9 are enlarged and internally threaded to carry glands 11 which hold in place the pipes 12 through which fluid will be forced to the brakes. This portion of the device is similar to the structureshown in the copending application.

The upper end of each c linder carries a removable head or cap 13 w iich extends upwardly and is hollow thus providing a pocket 14 to receive the upper end port-ion of the piston rod 15 and provide means for guiding sliding movement of the piston rod. A shoulder 16 is formed upon the piston rod to limit upward movement of the same and further serve to provide space above the piston 17 carried by the rod when the piston is in the raised position. This piston may be of any suitable construction providing a double acting piston but in the preferred form will be provided with an intermediate block 18 and upper and lower blocks 19, cups 20 being placed between the blocks and a securing nut 21 being provided upon the lower end of the piston rod to hold the blocks'in tight clamping engagement with the cups. It will thus be seen that the piston can force fluid through the pipes 12 when moving downwardly and can return fluid to the-cylinder 1 when pressure in the cylinder is discontinued and the piston returns to the normal position. A groove 22 is formed in theupper portion of the piston rod so that fluid may pass the rod and thus the formation of a vacuum or fluid cushion in the upper portion of the pocket 14 prevented.

The power cylinder l-extendsabove the upper ends of the heads 13 of the cylinders 2 and carries a cap 23 which is inthe form of a packing gland so that the plunger may slidably pass through the cap. This plunger may be formed as shown in Fig. 1 or it may be modified in its construction and formed as shown in Fig. 3. In the form shown in Fig. 1, the plunger is in the form of a tube 24 which extends into the cylinder and is provided at its lower end with a shoulder 26 to limit upward movement of the plum er; A hollow seat 27 is screwed into the ower end of the tube to support a cushioning piston 28 which is slidably mounted in the lower portion of the lunger and in its turn is hollow and provided at its upper end with a reduced port 29 norm-ally closed by a check valve 30 opening downwardly and yieldably held in a raised and closed position by a spring 31 which rests upon the hollow seat 32 provided in the bottom of the piston. A spring 33 is provided in the plunger above the piston and will be held under the desired pressure by a rod 34 which extends into and is in threaded engagement with the interior of the plunger. This rod extends upwardly above the piston and although it has been shown broken ofl", it is to be understood that it will be connected with a suitable treadlc such as shown in my co-pending application. An abutment washer 35 is provided. about the rod 34 at the upper end of the tube and engages a spring 36 which rests upon av washer 37 and serves tonormally retain the plunger in a raised position, nuts 38 being provided to hold the rod against turning .when not desired and further serve to hold the washer 35 in place. Itwill thus be seen that when the plunger is moved downwardly to force fluid from the cylinder 1 into the cylinders 2 the piston 28 may move upwardly and provide a cushion compensating for unusual strain. The check valve is intended to prevent fluid from passing upwardl through thepiston but will permit any uid which may leak past the piston to flow back into the upper end of the cylinder. It should be noted that the plunger does not completely fill the cylinder and therefore when moved downwardly the fluid can pass about the plunger and out through the side ports 6.

In the form shown in Fig. 3, a modified form of plunger has been shown. This plunger 39 extends through the cap 23 and has its inner portion 40 reduced so that when the plunger is forced downwardly against the action of the spring 41, the fluid in the cylinder 1 may be forced upwardly about this reduced portion and into the c linders 2 through the ports 6. Beneath he reduced portion 41 there has been provided a portion which is'further reduced to provide a uide-rod 42 which extends through a pac ing gland 43 at the bottom of the cylinder. If desired this guide rod portion 42 may be omitted and the lower end of the cylinder closed by a plug similar to the plug 44 shown in Fig. 1.

\Vhen this equalizer is put in place, the pipes 12 which extend from the wheel brakes will be connected with the appropriate cylinders 2 and the rod 34 shown in Fig. 1 or the rod 45 of the plunger 39 conected with a foot pedal positioned where it can be easily reached by the driver of the autoinobile. The equalizer will be secured to a suit able support by fasteners passed through openings in the bracket portion 46 and the device will then be ready for use. If liquid is used to apply the brakes instead of air 13 the pipes which lead from a suitable reservoir will be connected with the. necks and the cylinders 1 and 2 and pipes 12 filled. When pressure is applied to force the plunger of the cylinder 1 downwardly, the fluid in this cylinder will be forced into the cylinders 2 and the pistons of these cylinders forced downwardly thus applying even pressure upon the fluid in the cylinders 2 and causing the brakes to be applied at equal pressure. I i

There has thusfloeen provided a very ethcient means for olerating hydraulic brakes at even pressure a -dfurther there has been provided a pressure applying and equalizing device so constructed that the brake or brakes connected with one of the cylinders 2 may be operated when the brake or brakes operated by the other cannot be operated.

It is to be understood that theinvention is not confined to the. specific structure shown but may be modified in its construction. Therefore, such modifications are to be protected as will come within the scope of the following claims,

I claim:

1. A pressure equalizer comprising cylinders having closed upper ends and outlets in their "lower end portions, pistons slidablein said cylinders, a power cylinder provided with outlets communicating with said cylinders adjacent their upper ends and above the pistons, and a plunger piston en -tering the power cylinder and movable longitudinally therein for forcing fluid through the outlets thereof into the first mentioned cylinders above the pistons therein and impart sliding movement to the pistons.

2. A pressure equalizer comprising cylinders having outlets adjacent their lower ends, pistons in said cylinders for placing fluid in the cylinders under pressure when the pistons are moved toward the outlets,

a fluid container having .communication with the cylinders above the pistons, and means for applying pressure to fluid in said container to cause the fluid in the container and upper portions of the cylinders to act upon the pistons and move the pistons towards the outlets and apply even pressure upon fluid in the cylinders between the pistons and outlets.

3. A pressure equalizer comprising cylinders, each having an outlet and an inlet, pistons slidable in the cylinders between the inlets and outlets, and common means for forcing fluid under pressure into the cylinders through the inlets to act upon the pistons at even pressure and place fluid in the cylinders between the pistonsand outlets under pressure. v

4. The structure of claim 3 having each cylinder provided with a-cap having a-neck extension closed at its upper-end to provide downwardly.

municating' with said cylinders through the inlets, a cap for the power cylinder, and a plunger extending through the cap into the power cylinder for forcing fluid in the power cylinder through the inlets into the first mentioned cylinders above the pistons for forcing the pistons downwardly and applying even pressure to fluid beneath the pistons.

6. The structure of claim 5 having the plunger of the power cylinder in the form of a tube, an actuating rod extending into the upper end of said tube, an open seat in the lower end portion of said tube, a pistonin the lower end portion of said tube normally resting upon the seat, and a spring in the tube between the piston and rod and yieldably holding the piston upon the seat and permitting upward movement of the piston while the'plunger is moving downward in a pressure-applying stroke.

7. The structure of claim 5 having the plunger of the power cylinder in the form of a tube, an actuating rod extending into the upper end of said tube, an open seat in the lower end portion of said tube, a piston in the lower end portion of said tube normally resting upon the seat, and a spring in the tube between the piston and rod yieldably holding the piston against the seat, said piston being hollowand having a check valve therein yieldably held closed and opening downwardly.

8. The structure of claim 5 having the plunger of the power cylinder hollow, an open seat in the lower end portion of said. plunger, a piston slidable in the plunger and resting upon the seat, a spring in the plungerabove the piston, and an actuating element extending into the plunger and ad- 'justably connectedtherewith and engaging the upper end of said spring to compress the same and apply pressure upon said piston to yieldably hold the piston against movement ofl' of-the seat as the plunger moves downwardly.

9. The structure of claim 5 having the plunger of the power cylinder hollow, an open seatin thelower end portion of said plunger, a piston slidable in the plunger and resting upon the seat, and a spring in the plunger above the piston engaging the piston and yieldably holding the piston against movement ofl the seat as the'plunger moves 10. The structure of claim 5 having the plunger of the power cylinder hollow, an openseat in the lower end portion of said plunger, a piston slidable in the plunger and resting upon the seat, and a spring in the plunger above the piston engaging the piston and yieldably holding the piston against movement off the seat as the plunger moves downwardly, the piston being hollow and open at its lower end and having its upper end provided with a reduced port, an open seat in the lower end of the piston, a valve element in the piston and a spring in the piston holding the valve element in a raised position to close the port in the upper end thereof.

11. A pressure equalizer comprising cyl inders each having an outlet and an inlet, pistons slidahle in the cylinders between the the pistons,

inlets and outlets, a power cylinder communicatipg with said cylinders through the inlets, a cap for the power cylinder, and a plunger extending through the cap into the power cylinder for forcing fluid in the power cylinder through the inlets into the first mentioned cylinders above the pistons for forcing the piston downwardly and applying even pressure to fluid beneath said plunger having its portion within the power cylinder reduced to provide space between the piston and the walls of the cylinder and having its lower end portion further reduced to provide a stem extension extending through the bottom of the cylinder and constituting a guide to hold the plunger against side play.

In testimony whereof I afiix my signature.

OSCAR J. FR-OCK. 

